A fuel cell is a device that obtains electric power from hydrogen and oxygen. The fuel cell has recently attracted attention as a clean power source since the power generation produces only water. Such a fuel cell includes a unit cell having a low voltage ranging from 0.6 to 0.8 V. Thus, a currently available fuel cell stack is fabricated by stacking and serially connecting a plurality of unit cells composed of membrane electrode assemblies (MEAs) and separators to obtain high output. This fuel cell stack, however, has a problem that the stacking involves a lot of work steps and thus takes time and effort.
Meanwhile, there is known a fuel cell fabricated by forming a plurality of unit cells in a plane on a sheet of electrolyte membrane, forming an interconnector part for connecting adjacent unit cells, and connecting the plurality of unit cells in series (for example, see Patent Literature 1). Such a configuration has advantages capable of increasing the voltage with one sheet of electrolyte membrane and eliminating or reducing the work of stacking the unit cells.